Alert archive / Illinois / Flash Flood Warnings in 2026
Flash Flood Warning 43, NWS Quad Cities, IA
NWS Quad Cities, IA issued this flash flood warning at Aug 19, 2026, 6:36 PM CDT for Mercer County, Illinois. It was in force for 113 min. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Aug 19, 2026, 6:36 PM CDT (23:36 UTC)
- Expired
- Aug 19, 2026, 8:29 PM CDT
- In force
- 113 min
- Issued by
- NWS Quad Cities, IA
- Area
- Storm-based polygon
- Flood severity
- None
County Mercer County, IL
The radar
The Quad Cities radar (KDVN), 47 km from the middle of the area, began a volume at 23:40 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Lincoln, IL (KILX), launched 12:00Z, 11.6 hours before the alert went out and 215 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 310 J/kg
- Mixed-layer CIN
- -93 J/kg
- Mixed-layer LCL
- 917 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 17 m²/s²
- 0-3 km storm-relative helicity
- 63 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
What forecasters said that day
The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Quad Cities, IA wrote its last area forecast discussion before this flash flood warning went out at Aug 19, 6:25 PM CDT, 11 minutes earlier.
Area forecast discussion, Aug 19, 6:25 PM CDT, 11 minutes before
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Hazardous Weather Outlook National Weather Service Quad Cities IA IL 145 PM CDT Wed Aug 19 2026 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-201845- Buchanan-Delaware-Dubuque-Benton-Linn-Jones-Jackson-Iowa-Johnson- Cedar-Clinton-Muscatine-Scott-Keokuk-Washington-Louisa-Jefferson- Henry IA-Des Moines-Van Buren-Lee-Jo Daviess-Stephenson-Carroll- Whiteside-Rock Island-Henry IL-Bureau-Putnam-Mercer-Henderson- Warren-Hancock-McDonough-Scotland-Clark- 145 PM CDT Wed Aug 19 2026 This Hazardous Weather Outlook is for portions of north central Illinois...northwest Illinois...west central Illinois...east central Iowa...northeast Iowa...southeast Iowa and northeast Missouri. .DAY ONE...THIS AFTERNOON AND TONIGHT Isolated severe storms are possible this afternoon into early evening south of Interstate 80. Damaging winds, hail and localized flash flooding are the primary threats. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY Patchy fog, some locally dense with visibilities under one half mile, is possible during the Thursday morning commute. .SPOTTER INFORMATION STATEMENT... Spotter activation is possible this afternoon into early evening south of Interstate 80.
In the hours before
Special weather statement, Aug 19, 4:23 PM CDT, 2 hours 13 minutes before
Special Weather Statement
National Weather Service Quad Cities IA/IL
423 PM CDT Wed Aug 19 2026
IAZ088-089-099-ILZ025-026-034-035-192215-
Warren IL-Henderson IL-McDonough IL-Hancock IL-Henry IA-
Des Moines IA-Lee IA-
423 PM CDT Wed Aug 19 2026
...Slow-moving thunderstorms will impact portions of Warren,
Henderson, northwestern McDonough, northeastern Hancock, southeastern
Henry, Des Moines and northern Lee Counties through 515 PM CDT...
At 422 PM CDT, Doppler radar was tracking slow-moving thunderstorms
along a line extending from near Little York to near Iowa Army
Ammunition Plant to near Pilot Grove. Movement was southeast at 25
mph.
HAZARD...Funnel clouds and possibly weak, brief tornadoes, and 50
mph winds.
SOURCE...Radar indicated.
IMPACT...Isolated damage to roofs, siding and trees is possible.
Locations impacted include...
Burlington, Fort Madison, Monmouth, Oquawka, Nauvoo, West Burlington,
New London, La Harpe, Roseville, West Point, Dallas City, Danville,
Donnellson, Stronghurst, Kirkwood, Blandinsville, Salem, Little York,
Middletown, and Carman.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Conditions are favorable for the development of funnel clouds, and
possibly brief, weak tornadoes. The National Weather Service will
continue to closely monitor the situation, and may issue a Tornado
Warning if the threat increases. If you see a funnel cloud please
seek shelter indoors and then contact your local law enforcement
agency for relay to the National Weather Service.
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is occurring and may lead to localized flooding.
Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4052 9132 4074 9172 4081 9172 4091 9144
4107 9090 4107 9068 4094 9044 4081 9044
4051 9094
TIME...MOT...LOC 2122Z 308DEG 23KT 4103 9079 4075 9126 4075 9163
MAX HAIL SIZE...<0.75 IN
MAX WIND GUST...50 MPH
JTSSpecial weather statement, Aug 19, 5:12 PM CDT, 1 hour 24 minutes before
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</html>The office that day
Everything else NWS Quad Cities, IA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 19, 2:38 PM CDT | Special Weather Statement | DVN | Henry, Jefferson | 52 min |
| Aug 19, 2:53 PM CDT | Tornado Warning | DVN | Des Moines, Louisa | 24 min |
| Aug 19, 3:25 PM CDT | Special Weather Statement | DVN | Des Moines, Henry, Van Buren | 65 min |
| Aug 19, 4:23 PM CDT | Special Weather Statement | DVN | Des Moines, Lee | 52 min |
| Aug 19, 4:36 PM CDT | Flash Flood Warning | DVN | Des Moines, Henry, Lee | 2 hr |
| Aug 19, 5:12 PM CDT | Special Weather Statement | DVN | Lee | 63 min |
| Aug 19, 5:36 PM CDT | Special Weather Statement | DVN | Mercer | 39 min |
| Aug 19, 6:06 PM CDT | Flash Flood Warning | DVN | Mercer | 2 hr |
| Aug 19, 6:10 PM CDT | Special Weather Statement | DVN | McDonough | 65 min |
Nearby
Flash Flood Warnings in Illinois, 2026Every flash flood warning in 2026
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.